Chemical Senses Advance Access published online on March 17, 2009
Chemical Senses, doi:10.1093/chemse/bjp010
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Odorant Receptors from the Light brown Apple Moth (Epiphyas postvittana) Recognize Important Volatile Compounds Produced by Plants
1 The Horticultural and Food Research Institute of New Zealand Limited (HortResearch), Health and Food Group, Private Bag 92169, Auckland 1142, New Zealand 2 School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand 3 CSIRO, Food Futures Flagship—Division of Entomology, GPO Box 1700, Canberra, ACT 2601, Australia 4 The Horticultural and Food Research Institute of New Zealand Limited (HortResearch), Bioprotection Group, Private Bag 11030, Palmerston North 4442, New Zealand
Correspondence to be sent to: Richard D. Newcomb, The Horticultural and Food Research Institute of New Zealand Limited (HortResearch), Private Bag 92169, Auckland 1142, New Zealand. e-mail: rnewcomb{at}hortresearch.co.nz
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Abstract |
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Moths recognize a wide range of volatile compounds, which they use to locate mates, food sources, and oviposition sites. These compounds are recognized by odorant receptors (OR) located within the dendritic membrane of sensory neurons that extend into the lymph of sensilla, covering the surface of insect antennae. We have identified 3 genes encoding ORs from the tortricid moth, Epiphyas postvittana, a pest of horticulture. Like Drosophila melanogaster ORs, they contain 7 transmembrane helices with an intracellular N-terminus, an orientation in the plasma membrane opposite to that of classical GPCRs. EpOR2 is orthologous to the coreceptor Or83b from D. melanogaster. EpOR1 and EpOR3 both recognize a range of terpenoids and benzoates produced by plants. Of the compounds tested, EpOR1 shows the best sensitivity to methyl salicylate [EC50 = 1.8 x 10–12 M], a common constituent of floral scents and an important signaling compound produced by plants when under attack from insects and pathogens. EpOR3 best recognizes the monoterpene citral to low concentrations [EC50 = 1.1 x 10–13 M]. Citral produces the largest amplitude electrophysiological responses in E. postvittana antennae and elicits repellent activity against ovipositing female moths. Orthologues of EpOR3 were found across 6 families within the Lepidoptera, suggesting that the ability to recognize citral may underpin an important behavior.
Key words: citral, dose–response, Epiphyas postvittana, methyl salicylate, odorant receptor, plant volatile
Accepted 15 February 2009